The present invention relates to an electronic timepiece and more particularly to an electronic timepiece comprising a quartz crystal oscillator for producing a time standard signal and a frequency divider for dividing the frequency of the time standard signal to predetermined frequencies for driving a time display device. Such an electronic circuit employs a digital logic circuit comprising the complementary MOS transistor (hereinafter called as CMOST).
A conventional quartz crystal electronic timepiece comprises, as shown in FIG. 1, an quartz crystal oscillator 1, a frequency divider 2, a display driver 3 and a display device 4. Supply voltage is uniformly applied to each electronic circuit from a battery 10.
In the prior art, the voltage of the battery is applied to a part of the electronic circuit, such as the display driver and the display device which requires a comparatively higher voltage, and a lower voltage than the voltage of the battery is applied to the other part of the circuit, so that power consumption may be decreased. To this end, a CMOST in the lower voltage zone of the integrated circuit is made to have a lower threshold voltage. However, the produced CMOST does not always have a constant threshold voltage, because the voltage varies according to a slight difference in product condition.